Techniques for optimising long-term, large-scale capture–mark–resighting raptor studies: climb hard, band fast

Abstract

Context Efficiency of large-scale capture–mark–recapture (CMR) studies can be improved by developing accurate methods for predicting the window of opportunity in which banding can occur. Aims This research aimed to investigate potential efficiency improvements in a long-term CMR raptor study. The research focussed on: (1) developing selection processes for adopting CMR protocols; (2) testing methods for increasing the number of nestlings successfully banded; and (3) assessing the efficacy of visual identification (VID) bands for collecting re-sight data. Methods Ten selection criteria were developed into a robust CMR-technique selection process and used to assess marking techniques commonly applied to birds. Optimising banding effort by predicting banding dates using two different techniques a priori and a posteriori were tested against a traditional approach to the timing of banding. The cost (in time) to collect resight data at an active nest site was also measured. Key results The CMR selection criteria and parameters provided a transparent selection process and scored metal VID bands the highest for the study design. This provided individual recognition of marked birds up to the expected life-span of 14 years. Both techniques for predicting banding dates improved the proportion of whole clutches banded by 40%. The average time to identify both peregrine falcon adults of a breeding pair wearing VID bands was 30 min. Conclusions The two methods described here for predicting preferred banding dates are of particular value as efficient approaches to banding large numbers of nestlings are key to the success of CMR studies. All of the methods developed in this research can be applied to CMR studies of almost any bird species with a predictable seasonal breeding system. Implications Optimisation and cost effectiveness of CMR studies for seasonal breeding birds can be significantly improved by accurately predicting the window of opportunity in which banding of nestlings can be carried out, and also utilising VID colour bands for rapid collection of recapture data.